I agree with you on marketing and mobile - if the defaults are good enough on mobile then people are going to mostly use that. And while Firefox used to be hugely popular Chrome has really taken over its market share. Butnow Chrome has gone from a lean and simple browser to a bloated mess that chokes when you have too many tabs and starts using gigabytes of ram.
It has problems with memory, performance, rendering and battery drainage.
Every year I switch to Firefox and use it as a main browser. It usually goes for a month and then I need to switch again because Firefox has too many glitches.
Firefox has had a bad policy of not fixing the basics first before new features.
I do use Firefox as my main development browser still but that is because I’m more used to the developer tools than the alternatives.
In my experience, Chrome has problems with memory, performance, rendering and battery drainage. Every now and then I try to use Chrome (or a derivative) as secondary browser and I give up because it has noticeably higher latency for simple web page loads, and more likely to suffer irritating repaint flashes.
You're both right.
It's a common story -- people use browser A, start noticing a variety of problems, switch to browser B and everything is so much better. After a while, they start noticing a variety of problems, switch to browser A, and once again everything is so much better.
Those people are not being stupid, that is their real experience.
Sometimes the problem is in a web site (an update starts leaking memory, for example) and whatever browser is running gets blamed.
Sometimes it's just natural human bias—we want to see patterns, and we want there to be a solution ("just switch browsers!"), so we get selective in what we notice and don't notice.
Sometimes it's because profile cruft piles up, and resetting would fix it.
Sometimes the problems really are in one browser and not the other. There are plenty of legitimate problems to be found, and things change pretty rapidly.
But the comparison point is switching browsers, which also loses lots of state.
(In both cases, you can import a subset of your state into your new profile, and you'd probably get most of the performance advantages.)
I believe all browsers have been improving in their resistance to the accumulated state problem, but I also believe that all browsers are still susceptible to it.
Any time I've tried switching away it's more to see if I'm missing out on something... and it turns out I'm not.
My biggest issue was (maybe still is, I quit using Firefox last year) is that on wide color gamut displays, like every MacBook Pro, it renders colors completely wrong. So it would render literally every website, save black and white website, completely incorrectly.
My main browser these days is Safari (so I’m still enjoying a lot of browser bugs). When I really need something to work or need specific de tools I switch to Chrome. For me Firefox is in a middle ground between those two browsers, resulting in me never actually using it anymore.
I liked that too. That was before they decided to shut it down...
Several APIs that make powerful web applications possible are missing (e.g. WebUSB, various filesystem access APIs) and Firefox generally tends to lag behind Chrome when it comes to new APIs/web features.
The lower market share means that many web sites don't support it properly. For example, I need to keep a Chrome profile around for Zoom since the button doesn't even show up on Firefox, and when I tried to join a Teams meeting with Firefox, it failed in some non-obvious way, causing me to be late to a job interview (may have been due to some extension misbehaving or some config issue). I don't know if that's just because the sites don't test and do user agent sniffing, or whether Firefox is actually missing some APIs that would be required, but from a user perspective, it doesn't really matter, I can't use the browser for things I can do with Chrome.
I also still have occasional crashes.
WebUSB may not be the best example, as it was disabled by Chrome because there is no way to secure it. Though I agree in general that some APIs (WebGL) were experimental and behind a flag for too long in FF.
As a counterpoint, Firefox is/was ahead on some important APIs (WASM, U2f)
I have not shared your experience with Teams or Zoom. I use them both daily from FF on OSX.
Sometimes that is because chromium just implements anything they want and it's not in the spec.
But is Firefox an inferior browser? I think it used to be, but over the last couple years, it has made massive improvements in features and performance. I use it in both desktop and mobile, and I prefer it over Chrome.
As a software engineer, I rely heavily on my browser for work. For me, the multi-account containers in Firefox are the must-have feature. No other browser can offer the ease of separating multiple test accounts, and multiple gmail/gsuite accounts for multiple enterprises separate.
Also, I like how Lockwise on mobile is divorced from the browser, making it easy to use it to manage passwords across websites and apps.
Maybe the problem with Mozilla, then, is marketing. Maybe not enough people know that Firefox is much, much better than it used to be. Or maybe the general sentiment is echoed in your post. People don't feel that Mozilla is focused on writing good software, so they don't expect Firefox to be good.
Personally, I think the biggest cause for the loss of market share is simple: Safari is the default on iOS and Chrome is the default on Android, and population of mobile devices is exploding, and there are no mainstream mobile devices that are carrying Firefox with it.